Improvement in the manufacture of curved electrotype and stereotype plates



UNTTEE STATES PATENT OFFICE.

HENRY LOVEJOY, HENRY w. LOVEJOY, AND JAMES H. FERGUSON, OE NEW YORK, N. Y.

IMPROVEMENT IN THE MANUFACTURE 0F CURVED ELECTROTYPE AND STEREOTYPE PLATES.

Specilieation forming part of Letters Patent No. 86,02l, Caled January 19, 1869.

To all whom fit may concern:

Be it known that we, HENRY LOVEJOY, HENRY W. LOVEJOY, and J AMES H. FERGU- SON, all ofthe city, county, and State of New York, have invented a new and useful Process ot Manufacturing'Curved Electrotype or Stereotype Plates, ot" which the followingis a full, clear, and exact description, reference being had to the accompanying drawings, forming part of this specification, and in which- Figure l represents a sectional or edge View' Similar letters ot' reference indicate corresponding parts.

By none ot' the methods heretofore adopted can curved electrotype or stereotype plates be made from flat plates or forms without so altering the size in the direction ot the curve that the new or curved plate will not register7 with the original or iat plate or form, whereas it is very desirable in many cases that the fiat and curved plates should work together or register with each other-as, t'or instance, in colored or illuminated printing, and especially so in the printing ot' the several colors during one passage of the paper.

The Object of our invention is to produce the curved plates from the dat plates or forms without altering the length across the face.

To facilitate the explanation of the nature off the invention we will first refer brietiy to the well -known previous processes ot` forming curved electrotype or stereotype plates by way ot'showing why the same cannot assimilate with the original or tlat plates or forms, and of explaining how the ditliculty is obviated by our improvement. In one of these processes, after the impression has been taken from the lat plate, the mold has been bent to the full extentof the required curvature to make the curved plate, and then the metal cast or deposited on or in such curved mold. This method shortens the curved plate to an amount dependent upon the thickness or depth of themold and degree or extent ot' its curvature. In another of said processes the shell7 has been made dat in the usual way and then bent to the required extent ot' the curved plate. This moreorless lengthens the shell, according to the curvature and thickness of the shell and character ofthe surface, a smooth or plain surface not beingso much affected as adeeply-engravedone. In the third process the plate has been made dat in theusual way, and then bentto the fullcurve required. This also leugthens the plate to adegree dependent upon the curvature and thickness of the plate. Our improvement in a measure combines all these three processes. Thus the mold A is made fiat in the usual way, as represented in Fig. 1, and afterward is bent to a limited extent short of the full curvature required' to be given to the finished curved plate, as shown in Fig. 2. Aft-er depositing or casting in this partially-curved mold we further bend the shell or plate B to the full extent ot' the curvature required t'or the finished plate, as represented in Fig. 3. Now it will readily be seen that this subsequent bending ot' the shell or plate has a lengthening eiiect, which compensates for the shortening etl'ect produced by the bending ot' the mold, so that the duplicate or curved plate and original or tlat one are made to register. The degree ofcurvature which is given to the mold relatively to the curvature which the nished plate is required to have will depend on the relative thicknesses of the mold or plate; but when molds and plates ot'ordinary thickness are used we find in practice that the curvature given to the mold should be about half of that which the plateis to have.

In applying this invention to the manufacture ot' electrotypes the final curvature may be given to the shell before it is backed with the fusible metal or to the plate formed by the backing of the shell with fusible metal.

TVhat we claim, and desire to secure by Letters Patent, is

l. The process, substantially as herein described, ot' making curved electrotype or stereotype plates by tirst forming the impression in a flat mold, afterward giving said mold a curvature falling short of the required curvature ot' the `bend or duplicate plate to' be made, and after casting 0r depositing in such curved mold, subsequently bending the shell or plate to the full curvature required for the 1inished and duplicate plate, substantially as speciied.

2. Curved electrotype or stereotype plates made in the manner described, as a new arti.

cle of manufacture.`

HENRY LOVEJOY. HENRY W. LOVEJOY. JAMES H. FERGUSON.

Witnesses* OOR. R. DsosWAY, CHR. C'. LEIGH. 

